Automatic circuit breaker



Jan. 2, 1940. J, SACHS 2,185,524

AUTOMATIC CIRCUIT BREAKER Filed Oct. 4, 1958 3 SheBtS-Sheet 2 .ZJVI/ENDF :.7275 @Uh 555275 *frn/gy Jan. 2, 1940. J. sAcHs AUTOMATIC CIRCUIT BREAKER Filed` Oct. 4. 1938 3 Sheets-Sheetl 3 .tarngy /7 E'aahs h//" .7:

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Patented Jan. 2, `194.0 i

UNITED\STATES PATENT OFFICE AUTOMATIC CIRCUIT BREAKEB.

Joseph Sachs, West Hartford, Conn., assignor to Colts Patent Fire Arms Manufacturing Company, Hartford, Conn., a corporation of Connccticut Application October 4, 1938, Serial No. 233,265

28 Claims. (Cl. 20D-116) The present invention relates to an automatic bodily movable with the movable contact or concircuit breaker and is particularly adapted for tacts. incorporation in an automatic circuit breaker of Another object of the invention is to provide the general type disclosed vin my prior patent an improved general arrangement of parts which for Automatic circuit breaker No. 2,094,964 dated facilitates assembly and disassembly and which 5 October 5, 1937. The circuit breaker disclosed enables certain of the parts to be readily rein the said patent is responsive to only one conmoved for inspection, repair or replacement trolling condition, this is, an excess current conwithout disturbing other parts. y dition in one leg of an electric circuit. The cir- In accordance with the invention I provide cuit breaker embodying the present invention is various advantageous details' of construction and l0 essentially different in that it is responsiveto operation all of which will be lfully apparent either one of two different controlling conditions, from the following specification. as for instance an excess vcurrent condition in In the accompanying drawings I have shown either one of two legs of the circuit. one suitable embodiment of the invention, but it l5 While I do not necessarily so limit myself, a will be understood that the drawings are intendl5 circuit breaker embodying the present invention ed for illustrative DUIPOSCS Only and ere not t0 is particularly adapted for use as a motor be construed as defining or limiting the scope of starter. It is capable of carrying e, moderate the invention, ther claims forming a part of this overload for a predetermined short interval of Speeeetion being relied POD for thet Purpose time, but the design is such that automatic'open'- 0f the drawin l ing of both legs of the circuit will occur if the Figi is a front View 0f e Circuit breaker overload continues in either one of the two legs. emboiiying the invention' the front cover 'of the of the circuit for a longer interval of time. v enciosmg box being-emitted- A motor starter embodying the present inven- Fig; 2 is 9' Vertical Sectional View taken @ions tion is manually operable to close and open the iifietrilnnggmogf blgif' 1- and showing the over 25 3 is a provided connectible in two legs of the circuit glrixtl 3 4 of Fig' 1 the enclosing box being'- and each serving upon the attainment of excess current conditions in the corresponding circuit thuisa 12:2; gngnti'ita itlgswi so.

leg to release the movable contacts from the conl d-ci ui itl n trol of the operating member or handle and thus St'lc'tg ig siwrsinlssto 1 but omitting permit the circuit to automatically open indea5 pendently of the handle. n rilreecleos and Showing the parts m @en one if the'obiects m the invention is to pro' Fig. 6 is a transverse sectional view taken vide ascircuit breaker or motor starter of. the along the une 6.4.01 Fig. 1 and showing the type speciiied having a simple, inexpensive and cover of the enclosing bom e reliable mechanism for effecting the automatic pigra is e perspective view shewing various o release of the movable contact or contacts to parte of theeireut breeker mechanism seperated 40 permit automatic circuit opening movementv from each other in order that 'the ,details of thereof. When there is a handle the said conconstruction may be more reedny apparent tact or contacts are released from the control 111g, 3 is 9frsgmentery sectional view .taken ot the said handle, or handle operated actuating along the line ef Figl 2 and showing certain member, in the manner heretoforespecied. In4 0f he parts in their dosed-circuit;positions.I s 45 accordance with ythe invention two movable elec- Fig, v9 is` e View similar te Fig, s but s hewmg, tro-responsive means are\included in the methe parts in the positions which they assume chanical connection between the actuating memwhen the operating member or handle is ymoved ber and the member carrying the movable con-v to open-circuitposition.` so tact or contacts, these two electro-responsive Fie, 1 0 is a view simpel-W0 ms, s but shewing' 50 means normally servingto maintainthemechanthe .parts m the positions which they assume 'r ical connection and either of them uponelectrowhen the operating member or''handle is held responsive actionserving toy break the mechan-y in closed-circuit position and when automatic f ical connection. Preferably and as shown, these opening is effected by reason of excess lcurrent electro-responsive means are bi-metallic -strips in the left hand leg ofthe circuit. j ,55

Fig. 1l is a view similar to Fig. 8 but showing the parts in the positions which they assume when the operating member or handle is held in closed-circuit position and when automatic opening is effected by reason of excess current in the right hand leg of the circuit.

Referring to the drawings, I represents an insulating block or base which serves as a support for all of the electrical parts of the circuit breaker and for all of the mechanically operative parts. The base I is secured by means of screws 2, 2 to a bracket 2a which is connected with the rear wall of an enclosing box 3. The box 3 has a lremovable front cover 4 normally held in place by screws 5, 5. The cover 4 has a front opening adapted to receive the operating member or handie of the circuit breaker as will presently appear.

A three pole circuit breaker is shown, there being three wire terminals 6, 1 and 8 secured to the base near the top edge thereof and three other wire terminals 9, I and II secured to the base near the bottom edge thereof. Electrically and mechanically connected with the respective wire terminals 6, 1 and 8 are stationary contacts I2, I3 and I4 having downward exposed contact faces. Each of the stationary contacts I2, I3 and I4 constitutes one of a pair of such contacts, the other contact of each pair being similarly constructed and positioned but located toward the rear. These latter contacts will be referred to as the rear stationary contacts, the rear contact |5 for the right leg of the circuit being shown in Fig. 2A and the rear contact I6 for the center leg of the circuit bein shown in Figs. 3 and 4.

The rear stationary contact I5 at the right is carried by a conductor I1 at or near the rear of the base, this conductor being engaged by screws I8 and I9 which extend through the base to the front thereof. A screw similar to the screw I 9, is mounted at the front of the base, this screw being associated with a conductor 2| which carries the before-mentioned wire terminal 9. A heating unit to be presently described in detail is connected between the screws I3 and 20 and there 4is thus established a continuous electric circuit from the rear stationary contact I5 to the wire terminal '9. In similar manner the rear stationary contact at the left is electrically connected with the wire terminal I|, there being heater engaging screws 22 and 23 similar to the screws i8 and 20, and there being a conductor 24 at the front similar to the conductor 2|.

The rear stationary contact I6 at the center is carried by a conductor 25 at the rear of the base which extends downward to a position near the lower end of the base where it is engaged by a screw 26 extending forward to the front of the base and providing electrical connection with the wire terminal I0.

A contact carrying block 21 is movable vertically in a`manher to be presently described. This block 21 carries three pairs of bridging contacts scription-of onevof them will suice for all. Re-

ferring particularly to Fig. 7, it will be obiserved that the contacts 23, 28 constituting one pair are mounted on a bridging conductor 28* which is carried by th`e contact member 21. Preferably the' bridging contacts and their connecting conductor are readily detachable from block' 21 .so that they can be replaced if worn or burned.

Projecting upward from the block 21 is a fiat stud 3| having a narrowed portion 3|a and having laterally projecting teeth 3|, 3|b. The conductor 28 has a T-slot 28h therein, the entrance portion of which is of such width as to receive the narrowed portion 3| of the stud 3|. 'I'here is also provided a washer 32 having a T-slot 32al therein similar to the T-slot 28b but reversed as to position. A coil spring 33 is provided which is adapted to surround the stud 3|. In assembling the parts the spring 33 is placed on the stud Y3| and compressed. Then the washer 32 and the bridging connector 28 are placed on the stud, the entrance portions of their T-slots receiving the narrowed portion 3|a of the stud 3|. After being thus assembled the bridging conductor 28 and the washer 32 are permitted to move forward under the influence of the spring 33 until further movement is prevented by the laterally projecting teeth 3|b, 3|b. Thus the bridging connector is detachably and yieldably connected to the contact carrying block; and it can be readily removed by reversing the procedure last described. When the block is moved upward the movable contacts on the bridging connector can engage the corresponding stationary contacts, the spring 33 yielding as required and providing the neces- -sary contact pressure.

Carried by the base I is a frame which serves to carry all of the movable parts of the circuit breaker. This frame is approximately U-shaped in horizontal section, the legs of the U consisting of two parallel vertical side plates which project forward. As shown, the frame consists of three separate plates, there being a rear plate 34 and two separate side plates 35 and 36. 'I'he rear plate 34 is secured directly to the base as for instance by means of screws 31, 31 and the side plates 35 and 36 have slots such as 35a, 36 therein which receive tongues 34, 34a on the plate 34. The end portions of these tongues are riveted over to hold these side plates in place.

Mounted between the side plates 35 and 36 for rectilinear movement is an actuating member 36. A`s shown, this member 38 is a U-shaped metallic plate having slots 38, 388l in the side legs thereof which receive studs 39, 39 projecting inward from the side plates 35 and 36. Extending transverse'- ly between the side legs of the U-shaped plate 38 is a pin 40 having end extensions which project through slots 35h and 36h in the plates 35 and 36. It will be seen that the studs 39, 39' and the end extensions on the pin 40 serve as means for guiding the actuating member 38 for rectilinear movement between the two side plates 35 and 36.

The contact carrying block 21 is carried by a metallic member 4| which is U-shaped in vertical section, the legs of the U extending downward. 'Ihe block 21 is connected with the member 4| by means of screws or rivets 42. The front leg 4In of the plate 4| has tongues 4 Ib, 4|b projecting transversely therefrom, these tongues entering slots 35d in the side plate 35 and slots 36d in the side plate 36. 'Ihe rear leg 4Ic of the plate 4| has tongues 4 Id, 4 fi, projecting transversely therefrom, these tongues entering slots 35e in the side plate 35 and slots 36e in the side plate 36. The said lugs 4|b, 4|b and 4|d, 4|d thus serve to guide the member 4'Iiforrectilinear movement between the side plates 35 and 36. It will be observed that the member 4| is supported and guided entirely independently of the actuating member 38.

For convenience the member 4| together with the insulating block 21 and the contacts carried 76 ously at all of the contacts.

thereby will be referred to collectively as constituting the contact member of the circuit breaker. -All of the parts of the contact member are movable in substantial unison with each other so as to make and break the circuit simultaneand 36' of the frame and the other end of the spring is connected with a stud projecting from the rear leg 4Ic of the plate 4|.

In accordance with the invention, I provide two separate condition-responsive devices which are bodily movable with the movable contact or contacts and each of which is adapted to act separately from the other to mechanically release the said contact or contacts and thus permit automatic circuit-opening movement thereof. In the embodiment of the invention herein disclosed, the said condition-responsive devices are electro-responsive, each of them having at least a portion thereof inherently responsive to an electrical effect and normally bodily movable with the contact member and with the actuating member. The said velectro-responsive means normally serve to provide at least a portion of a mechanical connection so that the actuating member can cause the movement of the contact member to open and close the circuit. Upon electro-responsive action of either one of the electro-responsive means separately from` the other, the beforementioned mechanical connection is broken and the contact member is permitted to automatically move to its open-circuit position entirely independently of the actuating member. The details of the mechanical construction arrangement of the two electro-responsive means may be widely varied within the scope of my invention. One particular construction which has been found satisfactory is shown and will be described in detail.

The before-mentioned electro-responsive means associated with the actuating and contact members preferably comprises two thermostatic bi-4 metallic strips fixedly connected with one of the said members. As shown, there are two such strips 46 and 41 positioned at the sides of the contact member and connected respectively with integral extensions 4II and 4U on'the plate 4|'. The mechanical connecting means also comprises vtwo interconnected pivoted arms having operative connection with one of the said members. As illustrated, the two interconnected arms are integral with each other and constitute the end portions 48a and 48b of a transverse lever- 48 which is pivoted at 49 to the actuating member 38. The arms 48a and 48b extend transversely to positions at the outer sides of the respective side plates 35 and 36 and preferably they extend through slots 35f and 36f in the said side plates.

The before described bi-metallic strips 46 and 41 `screws 22 and 23.

otally connected at 52 to the operatingmember 50, as more clearly shown in Fig. 3, is a link 53,

the other end of the link being engaged by the before-mentioned pin 40 on the actuating member 38. A hole 4|,e in the front leg 4la of the member 4I provides clearance for the link 53. The link 53 serves to enable the operating member to move the actuating member 38 in either direction. Movement of the operating member 50 in the counter-clockwise direction is limited by a pin 54 extending transversely between the side plates 35 and 36.

As shown in Figs. 2 and 3, the inner portion of the operating member 50 cooperates with the link 53 to form an overset toggle, which holds all of the parts in closed-circuit positions. Pressure for maintaining the toggle in its overset or locked position as shown is provided by the spring 43. The pin 54 prevents movement of the operating member in the counter-clockwise direction beyond the position illustrated. When the operating member 50 is moved in the clockwise direction so asl to break the toggle, the parts are then .moved by the springs 43 and 5l to their open-circuit positions as shown in Fig. 4.

The bi-metallic strips 46 and 41 are deflectible by heat and as concer-,ns the broader aspects of manner of heating the said strips. Preferably,

however, there `are two separate means associated 'respectively with two legs of the circuit and with the said two bi-metallic strips, the said means serving upon the attainment of excess current conditions in either legof the circuit to cause the independent heating and deflection of the corresponding strip. As shown, there are two similar separate heaters 55, 55 having normally xed positions, these heaters being mounted on the insulating base I entirely independently of the frame which carries the contact member and the associated parts. The heater 55 at the right, serves as an electrical connection between the screws I8, and 20 and the heater 55 at the left, serves as an electrical connection between the The heaters are thus Areadily detachable and it will be clear that by removing the corresponding screws either of the heaters can be removed for inspection, repair or replacement.

The mechanical construction of the heaters can be widely 'varied but one suitable construction is shown in the upper portion of Fig. 7. Essentially each heater comprises two L-shaped strips 56 and 56a which are apertured to receive the attachment screws before-mentioned. Connected with the ends of the strips 56 and 56a is a section 'of high resistance heating wire 51 bent to a serpentine shape as shown. Preferably the L-shaped members 56 and 56e are cov'- ered by insulating plates 58 and 59 connected with the said members by means of hollow rivets 60 and 6I which receive the correspondingattachment screws. Other insulating plates 62 and 63 are provided at opposite sides of the resistance wire 51, these plates having extensions 62a and 63El which extend through slots in the insulating plate 56. The plates 6.2 and 63 are connected with each other by rivets 64, 64 which extend l through suitable spacing washers 65, 65. If desired the inner plate 63 may be perforated as shown to permit heat from the wire 51 to be more readily transmitted. By referring particularly to Fig. 6 it will be observed that the resistance wires of the two heaters are normally positioned in relatively close proximity to the bimetallic strips 48 and 41. The heaters are connected respectively in the right hand and left hand legs of the circuit and the resistance wires of the heaters are designed to carry normal current without excessive heating. However, upon attainment of excess current conditions in either of the said legs of the circuit the corresponding resistance wire is heated to a muchhigher temperature, and its heat is transmitted to the adjacent bi-metallic strip 46 or 41.

The operation of the circuit breaker under normal and abnormal current conditions will1 be more readily understood by reference to the fragmentary diagrammatic views which constitute Figs. 8, 9, l and 11. Fig. 8 shows the parts in closed-circuit positions, this view corresponding in this respect to Fig. l. The actuating member 38 is held in its upper position by means of the operating .member 50 and the link 53, and the contact member is correspondingly held in its upper position by reason of the engagement of the bi-metallic strips or latches 46 and 41 with the pivoted arms 48a and 4l!b which taken together constitute the lever 48. The contact member is biased for movement in the downward direction by the spring 43 as already explained, but it cannot so move by reason of the said engagement of the bi-metallic latches with the lever arms.

When the operating member is moved to break the toggle as shown in Fig. 4, the actuating member and the contact member move downward in unison to the positions shown in Fig. 9. This separates the movable contacts from the stationary contacts and breaks all three legs of the circuit simultaneously. It will be clear that by moving the operating member 50 upward or downward, the actuating lmember andthe contact member can normally be moved upward to close the circuit or downward to open the circuit.

As has already been explained, the heaters 55, 55 are connected in the two outer legs of the circuit and are so designed that under normal current conditions they remain at relatively low temperatures. However, upon the attainment of excess current conditions, the resistance wires of the heaters are heated to much higher temperatures and this heat is transmitted to the adjacent bi-metallic strips to cause outward deflection thereof. Obviously, a momentary excess current condition in either leg of the circuit will have no appreciable effect as time is required to heat the resistance wire and to transmit the heat from the wire to the adjacent bi-metallic strip or latch. However, if the excess current condition is continued in one leg of the circuit, as for instance in the left hand leg, the corresponding bi-metallic latch 41 is eventually heated so as to be deflected outward sufficiently to become disengaged from the corresponding pivoted arm 48b as shown in Fig. l0. This disengagement of the latch 41 from the arm 48b permits the contact member to be moved downward by the spring 43 thus opening the circuit, this downward movement of the contact member being entirely independent of the actuating member. It will be observed that this automatic opening of the circuit occurs as the result of the deilection of only one of the bi-metallic latches, as for instance 41, without any heating or deflection of the other bi-metallic latch, as for instance 46.

Fig. 10 shows the actuating member 38 in its closed-circuit position, it being assumed that it is so held by the operating member 50; and this figure therefore illustrates the fact that the automatic opening of the circuit occurs even though the operating member be held in closed-circuit position. However, if the handle is not held, or if it is first held and later released, the absence of the stress normally exerted by the spring 43 permits the toggle to be broken and permits the operating member to be thrown to its open-circuit position by means of the before-mentioned spring thus causing the actuating member 38 to also move to its open-circuit position as shown in Fig. 9. It will be understood that when the operating member is not held it starts to move to open-circuit position as soon as the toggle is broken. The operating member and also the actuating member therefore move while the contact member is moving, with the result that the actuating member is not at any time far behind the contact member.

It should be observed that movement of the actuating member to its lower open-circuit position brings the lever arms 48*i and 48b to the lower ends of the slots 35f and 361', the said arms being thus forced into their normal transverse positions as shown. In this way the disengaged arm 48b is returned to position for reengagement with the latch 41 as soon as the latch has sufliciently cooled. The fact that the actuating and contact members move almost simultaneously to their open-circuit positions greatly facilitates relatching as the disengaged arm is restored to relatchling position While the bi-metallic latch is still heated and deflected.

Fig. 11 is similar to Fig. 10, but shows the action which takes place when the excess current condition is in the right hand circuit instead of in the left hand circuit. Inasmuch as the manner of operation is similar, a repetition of the description is unnecessary.

While I have shownand described a circuit breaker responsive to excess current conditionsl in either one of two legs of a circuit, it is to be understood that as to some of the features of mechanical construction I do not necessarily so limit myself. The mechanical construction of the actuating and contact members and their associated parts has certain advantages which are not necessarily limited for use with two separate electro-responsive means.

What I claim is:

l. An automatic circuit breaker comprising in combination, a stationary contact, a contact movable out of or into engagement with the stationary contact to open or close the circuit, the said movable contact being biased for circuitopening movement but normally being mechanically held against such movement, two devices bodily movable with the movable contact and each adapted to act separately from the other to mechanically release the said contact and thus permit automatic circuit-opening movement thereof, and two separate means associated with the said devices and respectively causing each of them to act in response to a predetermined condition.

2. An automatic circuit breaker comprising in combination, a stationary contact, a contact movable out of or into engagement with the stationary contact to open or close the circuit, the

"said movable contact being biased for circuitopening movement but being mechanically held against such movement, and two devices bodily movable with the movable contact and each adapted t o respond to a predetermined thermal condition and thereupon act separately from the against such movement, two electro-responsive means each having atleast a portion thereof inherently responsive to an electrical effect and` normally movable bodily with the contact member, each of the said means upon electro-responsive action thereof serving separately from the other to mechanically release thecontact member and thus permit automatic circuit-opening movement thereof, and means for connecting the said electro-responsive means in the respective legs of the circuit so as to cause electro-responsive action of either ofthe said means upon the l attainment of excess current conditions in the corresponding leg of the circuit.

4.' The combination in an automatic circuit breaker, of a stationary contact,l a contact movable out of or into engagement with the stationary contact to open or close the circuit, the' said movable contact being biased for circuit-opening movement, and two bi-metallic strips bodily movable with the movable contact and normally cooperating with each other to form portions of a mechanical connection which holds the movable contact against circuit-opening movement, each of the said strips being adapted to respond to a predetermined thermal condition and thereupon act separately from the other to release the movable contact and thus permit automatic, circuit-opening movement thereof.

5.,In an automatic circuit breaker, the com` bination of a stationary contact, a movable contact. a movable actuating member normally adapted to move the movable contact to open or vclose the circuit, f means biasing the movable contact toward its open-circuit position independently of the actuating member, two devices bodily movable with the movable contact and the actuating member and each adapted to act separately from the other to mechanically disconnect the movable contact from the actuating member and thus permit automatic circuit-opening movement of the said contact independently of the actuating member, and two separate means associated with the devices and respectively causing'each of them to act in response to a predetermined condition.

6. In an automatic circuit breaker, the combination of a stationary contact, a movable contact, a movable actuating member normally adapted to move the movable contact to open or close the circuit, means biasing the movable contact toward its open-circuit positionindependently of the actuating member, two devices bodily movableT with the movable contact and the actuating member and each adapted to respond to a predetermined thermal condition and thereupon act separately from the other said device to mechanically disconnect the movable contact from thel actuating member' and thus permit automatic circuit-,opening movement of the said Contact independently of the actuating member, anda means associated with one of the said devices and causing it to be heated in "response toya predetermined electrical condition in the circuit.

7. In an automatic circuit breaker, the com- 4 bination of a stationary contact, a movable contact, a movable actuating member normally adapted to move the movable lcontact to open or close the circuit, means biasing the movable contact toward its open-'circuit position independently of 'the actuating member, two devices bodily movable with the movable contact and the actuating member and forming portions of -the mechanical connection between them, each of the said devices being adapted to act separately from the other to mechanically disconnect the movable contact from the actuating member and thus permit automatic circuit-opening move- 'ment of the said contact independently of the lactuating member, two separate means associated with the devices and respectively causing each of them to act in response to a predetermined condition, a pivcted operating member biased toward its open-circuit position, and toggle links operatively connecting the operating member with the actuating member, the said links when in. overset position holding the operating member in closed circuit .position and being normally vheld in their said overset position as the result of pressure transmitted from the contact to the actuating member by means ofthe said mechanical connection. f

8. In an automatic circuit breaker, the combination of two stationary contacts connectible respectively in two legs-of a circuit, a movable contact member having two contacts movable in unison therewith and with each other and connectible respectively in the said legs of the circuit, the said movable contacts being adapted to simultaneously engage and disengage the respective stationary contacts, a movable actuating member normally adapted to move the contact member to open or close the said legs of the circuit, means biasing the contact member toward its open-circuit position independently of the actuating member, two electro-responsive means each having at least a portion thereof inherently responsive to anclectrical eifectfand normally movable bodily with the contact and actuating members, each of thel said means upon electroresponsivev action thereof serving separately from the other to mechanically disconnect the contact member from the actuating member and thus permit the said contact member to automatically move independently to its open-circuit position, and means for connecting the said electro-responsive means -in the respective legs of the circuit so as to cause electro-responsive action of either of the said means upon the attainment of excess current conditions in the corresponding leg of the circuit.

9. In an automatic circuit breaker, the combination of twc stationary .contacts connectible respectively in two legs of a circuit, a movable contact member having two contacts movable in unison therewith and with each other and con-l nectible respectively in the said legs of the cirthe contact and actuating members, each ofthe said strips upon deiicction serving separately from the other to mechanically disconnect the contact member from the actuating member and thus permit the said contact member to automatically move independently to its open-circuit position, and two separate means associated respectively with the said legs of the circuit and with the said bi-mctallic strips and serving upon the attainment of excess current conditions in either leg of the circuit to cause the independent heating and deilection of the corresponding strip.

10. In an automatic circuit breaker, the combination of two stationary contacts connectible respectively in two legs of a circuit, a movable contact member having two contacts movable in unison therewith and with each other and connectible respectively in the said legs of the circuit, the said movable contacts being adapted to simultaneously engage and disengage the respective stationary contacts, a movable actuating member normally adapted to move the contact member to open or close the said legs of the circuit, means biasing the contact member toward its open-circuit position independently of the actuating member, two bi-metallic strips deflectible by heat and normally movable bodily with the contact and actuating members, each of the said strips upon deflection acting separately from the other to mechanically disconnect the contact member from the actuating member and thus permit the said contact member .to automatically move independently to its open-circuit position. and two separate stationary heaters connected respectively in the said legs of the circuit and positioned adjacent the said bimetallic strips and serving upon the attainment of excess current conditions in either leg of the circuit to cause the independent heating and denection of the corresponding strip.

11. The combination in an automatic circuit breaker, of a' stationary contact, a movable actuating member, a movable contact member having a. contact adapted to engage and disengage the stationary contact, the said actuating member being normally mechanically connected with the actuating member so as to move in unison therewith to open or close the circuit; means biasing the contact member toward its open-circuit position independently of the actuating member, and two bi-metallic strips deiiectible by heat and normally movable bodily with the said contact and actuating members and constituting portions of the mechanical connection between them, each of the said strips upon deection acting separately from the other to release the contact member from the actuating member and thus permit the entire contact member to automatically move as a unit to its open-circuit position independently of the actuating member.

12. 'I'he combination in an automatic circuit breaker, of a stationary contact, a movable actuating member, a movable contact member having a contact adapted to engage and disengage the stationary contact, the said actuating member being normally mechanically connected with the actuating member so as to move in unison therewith to open or close the circuit. means biasing the contact member toward its opencircuit position independently of the actuating member, and two bi-metallic strips defiectible by heat and normally movable bodily with the said contact and actuating members and cooperating witheach other to jointly provide a mechanical connection between them, each of the V of any deflection of the other strip to release the contact member from the actuating member and thus permit the entire contact member to automatically move as a unit to its open-circuit posiv tion independently of the actuating member.

13. The combination in an automatic circuit breaker, of a stationary contact, a movable actuating member, a movable contact member having a contact adapted to engage and disengage the stationary contact, the said actuating member being normally mechanically connected with the actuating member so as to move in unison therewith to open or close the circuit, means biasing the contact member toward its open- 'circuit position independently of the actuating member, two thermostatic bi-metallic strips deflectible by heat and normally movable bodily with the saidcontact and actuating member and constituting portions of the mechanical connection between them, each of the said strips upon deiiection acting separately from the other to release the contact member from the actuating member and thus permit the contact mem-- ber to automatically move to its open-circuit position independentlyv of the actuating member, a pivoted operating member biased toward its open-circuit position, and toggle links operatively connecting the operating member with the actuating member, the said links when in overset position holding the operating member in closed circuit position and being normally held in their said overset position as the result of pressure transmitted through the bi-metallic strips to the actuating member.

14. The combination in an automatic circuit breaker, of two stationary contacts connectible respectively in two legs of a circuit, a movable actuating member, a movable contact member having two contacts movable in unison therewith and with each other and connectible respectively in the said legs of the circuit, the said movable contacts being adapted to simultaneously engage and dlsengage the respective stationary contacts and the said contact member being normally mechanically connected with the actuating member so as to move in unison therewith to open or close the said legs of the circuit, means biasing the contact member toward its open-circuit positlon independently of the actuating member, two bi-metallic strips deflectible by heat and normally movable bodily with the said contact and actuating members and constituting portions of the mechanical connection between them, each of the said strips upon deflection acting separately from the other to release the contact member from the actuating member and thus permit the said 'contact member to automatically move independently to its open-circuit position, and two separate means associated respectively with the said legs of the circuit and with the said bi-metallic strips and serving upon the attainment of excess current conditions in either leg of the circuit to cause the independent heating and deection of the corresponding strip.

15. The combination in an automatic circuit breaker, of two stationary contacts connectible respectively in two legs of a circuit, a movable actuating member, a movable contact member having two contacts movable in unison therewith and with each other and connectible respectively in the said legs of the circuit, the said movable contacts being adapted to simultaneously engage and disengage the respective stationary contacts and the said contact member being normally mechanically connected with the actuating memamaca:

ber so as to move in unison therewith toopen or close the said legs of the circuit, means biasing the contactmember toward its open-circuit position independentlyof the actuating member, Itwo bi-metallic strips deilectible by heat and normally-movable bodily with the said contact and actuating members and constituting portions of the mechanical connection between them, each of the said strips upon deflection acting separately from the other to release the contact member from the actuating member and thus permit the said contact member to automatically move independently to its open-circuit position, and two separate heaters connected respectively in the said legs of the circuit and positioned adjacent the saidv bi-metallic strips and serving upon the attainment of excess current conditions in either leg of the circuit to cause the independent heating and deiiection of the corre-l sponding strip.

16. An automatic circuit breaker comprising in combination, a stationary contact, a movable contact member having a contactadaptedto engage and disengage the stationary contact, means biasing the contact member toward its contact-disengaging open-circuit position, and a v mechanical connection adapted to normally hold the contact member in its closed-circuit position, the said mechanical connection comprising two interconnected movable arms and also comprising two latches bodily movable with the contact member and electro-responsively movable out of their normal relationship thereto. the said latches normally engaging the respective arms so as to jointly maintain the mechanical connection which normally holds the contact member and each of the said latches upon electroresponsive movementserving independently of any movement of the other latch to disengage its corresponding arm so as to thus break the said mechanical connection and permit automatic circuit-opening movement `of the contact member.

17. An automatic circuit breaker comprising in combination, a stationary contact, a movable actuating member, a movable contact member having a contact adapted to engage and dis'engage the stationary contact, means biasing the contact member towardl its contact-disengaging open-circuit position independently of the actuating member, and a mechanical connection between the actuating and contact members nor?. mally enabling the former to effect movement l of the latter to open and close the circuit, the said mechanical connection` comprising two interconnected movable arms having operative connection with one of the last said members and also comprising two bodily movable latches carried by the other ofthe last saidY members and electro-responsively movable out oi their normal relationship thereto, the said latches normally engaging the respective arms so as to jointly maintain the mechanical connection betweenthe two members and each-of thesaid latches upon' electro-responsive movement Aserving independently of any movement of the\other latch to disengage itscorresponding arm so as to kthus break the said mechanical connection and permit circuit-opening movement of the contact member independently of the actuating'member.

` 18. An automatic circuit breaker comprising in combination, a stationary contact, a movable actuating member, a movable contact member having a contact adapted to engage and disengage the stationary contact, means biasing the contact4 member toward its contact-disengagng open-circuit position independently of the actuating member, and a mechanical connection be- Amechanical connection comprising two interconnected movable arms having operative connection with one of the last said members and also comprising two bi-metallic latches carried by the other of the last 'said members and deiiectibie outv of their normal relationship thereto when heated,4 the said latches normally engaging the respective arms so as to jointly maintain the mechanical connection between the two members and each' of the said latches upon being heated and deflected serving independently of lany heating and deflection of the other latch to disengage its corresponding arm so as to thus break the said mechanical connection and permit circuit-operaia ing movement of the contact member independently of the actuating member. Y 19. An automatic circuit breaker comprising in combination, a stationary contact,- a movable actuating member, a movable contact member having a contact adapted to engage and disengage the stationary contact, means biasing the contact member toward its contact-disengaging opencircuit position independently of the actuating member, `a mechanical connection between the actuating and contact members normally enabling the former to effect movement of the latter to open and close the circuit, the said. mechanical connection comprising two interconnected movable arms having operative connection with one of the last said members and also comprising two bi-metallic latches carriedby the other oi the last 7said members and deiiectible out of their normal relationship thereto when heated', the said latches normally engaging the respective arms so as to jointly maintain the mechanical connection between the two members and each of the said latches upon being-heated and deiiected serving independently of any heating and deiieotion of the other latch to disengage its cor-v responding arm so as to permit the arm tomove contact member, and means serving upon movement of the members to open-circuit positions to restore the arms to their normal relationship with respect to the said latches.

20. An automatic circuit breaker comprising 'l in combination. a stationary contact, a movable actuating member, a movable contact member having a contact adapted to engage and disengage the stationary contact, means biasing the con-` tact member toward its contact-disengaging opencircuit position independently of the actuating member, a mechanical connection between the actuating and contact members normally enabling the former to effect movement of the latter to open and close the circuit. the said mechanical connection compris g two interconnected pivoted arms having orative connection with'one of `the last said l embers and also comprising 'two' bi-metallic `latches carried by the other of the flst said. members and deflectible out voffftheir normal relationship thereto when heated, the said latches normally engaging the respectiveparms so as to jointly maintain the mechanical connection between the two members and each of the said latches upon being heated and deected serving independentto 4thus break the said mechanical connection and permit circuit-opening movement of the contact member independently of the actuating member, and means connected in the circuit and associated with one of the bi-metallic latches and serving upon the attainment of excess current conditions in the circuit to cause the heating and deiiection of the last said latch.

21. An automatic circuit breaker comprising in combination, two stationary contacts con-4 nectible respectively in two legs of a circuit, a movable actuating member, a movable Contact member having two contacts movable in unison therewith and with each other and connectible respectively in the said legs of the circuit, the said movable contacts being adapted to simultaneously engage and disengage the respective stationary' contacts, means biasing the contact member toward its contact-disengaging opencircuit position independently of the actuating member, a mechanical connection between the actuating and contact members normally enabling the former to effect movement of the latter to open and close the circuit, the said mechanical connection comprising two interconnected pivoted arms having operative connection with one of the last said members and also comprising two bi-metallic latches carried by the other of the last said members and deiiectible out of their normal relationship thereto when heated, the

said latches normally engaging the respective arms so as to jointly maintain the mechanical connection between the two members and each of the said latches upon being heated and deflected serving independently of any heating and deection of the otherlatch to dsengage its co1'- responding arm so asto thus break the said mechanical connection and permit circuit-opening movement of the contact member independently of the actuating member, and two separate means associated respectively with the said legs of the circuit and with the said bi-metallic strips and serving upon the attainment of excess current conditions in either leg of the circuit to cause the independent heating and deection of the corresponding strip.

22. An automatic circuit breaker comprising in combination, two stationary contacts connectible respectively in two legs of a circuit, a movable actuating member, a movable contact member having two contacts movable in unison therewith and with each other and connectible respectively in the said legs of the circuit, the said movable contacts being adapted to simultaneously engage and disengage the respective stationary contacts, means biasing the contact member toward its contact-disengaging opencircut position independently of the actuating member, a mechanical connection between the actuating and contact members normally enabling the former to effect movement of the latter to open and close the circuit, the said mechanical connection comprising two interconnected pivoted arms having operative connection with one of the last said members and also comprising two loi-metallic latches carried by the other of the last said members and delectlble out of their normal relationship thereto when heated, the said latches normally engaging the respective arms so as to jointly maintain the mechanical connection between the two members and each of the said latches upon being heated and deflected serving independently of anyheating and deflection of the other latch to d1sengage its correspondingarm so as to thus break the said mechanical connection and permit circuit-opening movement of the contact member independently of the actuating member, and two separate stationaryheaters connected respectively in the said legs of the circuit and positioned adjacent the said bi-metallic strips and serving upon the attainment of excess current conditions in either leg of the circuit to cause the independent heating and deflection of the corresponding strip.

23. An automatic circuit breaker comprising in combination, a stationary contact, a movable actuating member, a movable contact member having a contact adapted to engage and disengage the stationary contact, means biasing the contact member toward its contact-disengaging open-circuit position independently of theactuating member, and a mechanical connection between the actuating and contact members normally enabling the former to eiect movement of the latter to open and close the circuit, the said mechanical connection comprising two interconnected arms having direct pivotal connection with one of the last said members and also comprising two bi-metallic latches carried by the other of the last said members and deectible out of their normal relationship thereto when heated, the said latches normally engaging the respective arms so as to jointly maintain the mechanical connection between the two members and each of the said latches upon being heated and deiiected serving independently of any heatingy and deilection of the other latch to disengage its corresponding arm so as to thus break the said mechanical connection and permit circuit-opening movement of the contact member independently of the actuating member.

24. An automatic circuit breaker comprising in combination, a stationary contact, a movable actuating member, a movable contact member having a contact adapted to. engage and disengage the stationary contact, means biasing the Contact member toward its contact-disengaging open-circuit position independently of the actuating member, and a mechanical connection between the actuating and contact members normally enabling the former to effect movement of the latter to open and close the circuit, the said mechanical connection comprising a single lever directly pivotally connected with one of the last said members. and including two oppositely extending rigidly connected arms and the said connection also comprising two bi-metallic latches carried by the other of the said members and deectible out of their normal relationship thereto when heated, the said latches normally engaging the respective arms so as to jointly maintain the mechanical connection between the two members and each of the said latches upon being heated and devected serving independently of any heating and deflection of the other latch to disengage its corresponding arm so as to thus break the said mechanical connection and permit circuit-opening movement of the contact member independently of the actuating member.

25. In an automatic circuit breaker, the combination of a main frame having two side plates' spaced apart, an operating member movably connected with the side plates of the frame, an actuating member re'ctillnearly movable between the' frame side plates and guided thereby, means operatively connecting the operating member with the actuating rmember, a contact member rectilinearly movable between the frame side plates and guided thereby independently of the actuating member, the said contact member carrying a movable contact, a stationary contact positioned to be engaged and disengaged by the movable contact, means biasing 'the contact member toward its contact-disengaging opencircuit position independently of the actuating member, and a mechanical connection between the actuating and contact members normally enabling the former to effect movement of the latter to open and close the circuit, the said mechanical connection comprising two interconnected pivoted arms having operative connection with one of the last said members and also comprising two bi-metallic latches carried by the other of the last s'aid members and deflectible out of their normal relationship thereto when heated, the said latches normally engaging the respective arms so as to jointly maintain the mechanical connection between the two members and each of the said latches upon being heated and deected serving independently of any heating and deflection of the other latch to disengage its corresponding arm so as to thus break the said mechanical connection and permit circuit-opening movement of the contact member independently of the actuating member.

26. In an automatic circuit breaker, the combination of a main frame having two side plates spaced apart, an operating member movably connected with the side plates of the frame, an actuating member rectilinearly movable between l the frame side plates and guided thereby, means operatively connecting the operating member with the actuating member, a contact member rectilinearly movable between the frame side plates and guided thereby independently of the actuating member, the said contact member carrying a movable contact, a stationary contact positioned to be engaged and disengaged by the movable contact, means biasing the contact member toward its contact-disengaging 'open-circuit position independently of the actuating member, and a mechanical connection between the actuating and contact members normally enabling the former to eiiect movement of the latter to open and close the circuit, the said mechanical connection comprising two interconnected pivoted arms 'having pivotal connection with one of the last said members and extending in opposite directions to positions at the outer sides of the respective side plates and the said mechanical connection also comprising two bimetallic latches carried byv the other of the last said members and deilectible out of their normal relationship thereto when heated, the said latches being .positioned at the outer sides of the said side plates and normally engaging the respective arms so as to jointly maintain the mechanical connection between the two members and each of the said latches upon being heated and deflected serving independently of any heating and deflection of the other latch to disengage its corresponding arm so-as to thus break the said mechanical connection and permit circuitopening movement of the contact member independently of the actuating member.

27. In an automatic circuit breaker, the combination of a main frame having two side plates spaced apart, an operating member movably connected with the side plates ofthe frame, an actuating member rectilinearly movable between the frame side plates and guided thereby, means operatively connecting the operating member with the actuating member, a contact member rectilinearly movable between the frame side plates and guided thereby independently of the actuating member, the said contact member carrying a movable contact, a stationary contact positioned to be engaged and disengaged by the movable contact, means biasing the contact member toward its contact-disengaging opencircuit position independently of the actuating member, a mechanical connection between the actuating and contact members normally enabling the former to effect movement of the latter to open and close the circuit, the said mechanical connection comprising two interconnected pivoted arms having pivotal connection with one of the last said members and extending in opposite directions to positions at the outer sides of the respective side plates and the said mechanical connectionalso comprising two bi-metallic latches carried by the other of the last said members and deilectible'out oi their normal relationship thereto when heated, the said latches being positioned at the outer sides of the said side plates and normally engaging the respective arms so as to jointly maintain the mechanical connection between the two members and each of .the said latches upon being heated and deected serving independently of any heating and deection of the other latch to disengage its corresponding arm so as to thus break the `said mechanical connection and permit circuit-opening movement of the contact member independently of the actuating member, and two separate stationary heaters connected respectively in the said legs of the circuit and positioned adjacent the said bi-metallic strips and serving upon the attainment of excess current conditions in either leg of the circuit to cause the independent heating and deflection of the corresponding strip.

28. The combination in an automatic circuit breaker, of an insulating base, a main frame on the base, an operating member movably mounted on the main frame, an actuating member carried by the frame and guided thereby for movement in a fixed path, means operatively connecting the operating member with the actuating member, a contact member carried by the frame and guided thereby independently of the actuating member for movement in a xed path, the said contact member carrying-movable contacts and being normally movable with the actuating member, stationary contacts mounted on the base independently of the frame and positioned to be engaged and disengaged by the respective movable contacts, means on the frame biasing the contact member toward its contactdisengaging open-circuit position independently of the actuating member, two bi-metallic strips deilectible by heat and normally movable bodily with the said contact and actuating members, each of the said strips upon deflection serving separately from the other to mechanically disconnect the contact member from the actuating member and thus permit the said contact member to automatically move independently to its open-circuit position, and two separate stationary heaters mounted on the base independently of the frame and connected respectively in the said legs of the circuit, the said heaters being positioned adjacent the respective bi-metallic strips and serving upon the attainment of excess current conditions in either leglof the circuit to cause the independent heating and deection of the corresponding strip.

JOSEPH SACHS. 

